All too often they're placed in drawers or stuffed into wallets, never to be seen again. Some $1.7 billion of the $110 billion gift cards bought in 2012 will go unused, according to estimates from research company CEB TowerGroup.

If you're not happy about the store your gift card is from, don't let the money go to waste. You have options, such as trading it in for cash or airline miles.

But the first step to take when you get a gift is to register it on the company's website, says Scott Gamm, founder of HelpSaveMyDollars.com. Registration creates a record of how much money is on the card and will protect you in case you lose the card. Many companies, including coffee chain Starbucks, offer gift card registration. Just check the card provider's website to see if it's offered.

Mobile apps also can help you keep track of your cards. The Gyft app even will alert you if you are near a store that you have a card for. It stores both electronic and plastic gift cards.

Here are six ways to put a gift card to use:

1. Turn it into cash: If you have an unwanted gift card, websites such as PlasticJungle.com, GiftCards.com and CardPool.com will pay you up to 92 percent of the card's value, depending on how easy it is to resell. For a $100 Target gift card, all three are paying $92. Depending on the store the gift card is for, you may have to mail the plastic card in, but in many cases just typing in the card number works. You're then paid through PayPal or by check. You need to have at least a $25 balance on the card to sell it on PlasticJungle.com and CardPool.com and $20 to sell it on GiftCards.com.

2. Think outside the card: Even though a card has a specific store name on the front, you might be able to use it in the parent company's other stores. For example, an Old Navy gift card can be used at Gap, Banana Republic, Athleta stores and on Piperlime, the company's online store. Similarly, TJX Cos. Inc. gift cards can be used at TJ Maxx, Marshalls or at Home Goods stores.

3. Trade for miles: A lingering gift card balance can bring you closer to a dream vacation. United Airlines customers enrolled in their MileagePlus program can exchange gift cards for award miles through the airline's website. A $25 gift card is currently worth 1,000 award miles. United Airlines accepts gift cards from more than 100 stores. The gift card must have at least $15 on it for the airline to accept it.

4. Give to those in need: Many charities, such as Goodwill, will take your gift card and distribute it to those who can put it to use. Call your favorite charity and see if it has a gift card program.

5. Swap for another card: Cards also can be flipped for another retailer. On PlasticJungle.com, you can quickly convert your card into an electronic gift card for Amazon.com.

PlasticJungle.com also charges less if you want to make the switch. Even though the website will pay $92 for a $100 Target gift card, it will give you $94.50 if you choose to turn it into an Amazon card.

6. Re-gift it: You can always re-gift a card to someone who would appreciate it more. You'll get rid of the card and you won't have to buy a gift.

The Gyft app, which stores gift cards on smartphones, also enables you to re-gift the cards. The recipient doesn't need to have the Gyft app downloaded. The gift card can be emailed as an electronic gift card or it can be posted on a Facebook account.